1. Field of the Invention
The present invention relates to an abrasive sheet and a method of manufacturing the same, and more particularly, to such an abrasive sheet that is effective for use in an automobile repairing industry, and method of manufacturing the same.
2. Description of Related Art
In the present state of the art of the automobile repairing industry, various kinds of techniques are utilized for repairing external plates of automobiles such as bonnets, doors and the like, when damaged due to automobile accidents, within an shorter period of time and at lower cost in order to meet the customer's demands. In the prior art, the damaged portions on the external plates of the automobiles are typically repaired in the following manner.
Initially, a damaged recess portion of a plate is processed for restoration to its original shape by a panel beating process. Thereafter, any previous paint, if remaining, on the surface to be repaired is removed by using, for example, an abrasive paper of coarse grains to such degree that an underlying steel material becomes exposed. Then, cleaning of the surface is effected using some solvent, and the surface is coated with a putty. After the putty is hardened up to such point that the sanding can be done, the surface is sanded to a flat condition by use of the abrasive paper of coarse grains. Then, the surrounding surface thereof is flattened with the use of the abrasive paper by feather edging and giving teeth. Next, the surface is coated with a primer surfacer by a spray gun, and after it is hardened, the abrasive paper of fine grains is used for smoothing the surface. Then, the surface is coated with an over-coating paint by a spray gun. Furthermore, any dust, if present on the surface, is removed by using a water-proof abrasive paper of very fine grains, and a skin or surface conditioning is effected using the water-proof abrasive paper and/or a fine compound buffing. Finally, a polishing is performed by using a very fine and/or a super fine compound.
In the prior art repairing procedure as described above, due to the spraying operation of the over coating paint by the spray gun in atomized form, it is unavoidable that there is an orange peel always produced after hardening and drying of the paint material. More particularly, such an orange peel may have a different form or shape depending upon several factors including viscosity, surface tension and fluidity of the paint material when a particle in atomized paint material is re-combined with other particles on the painted surface; velocity of volatilization of the solvent; diameter of the spray gun; pressure and flow rate of air; flow rate of the paint material; distance to the surface to be painted; angle of atomization; and the surrounding conditions such as temperature, humidity, etc,. Although it is normally required in a repair-painting operation that an orange peel on a newly painted surface should substantially be matched to the existing orange peel on the surrounding area, there may frequently be some difference therebetween due to the effect of the factors as above. In order to match both orange peels, it is common practice to polish the newly painted surface in a buffing process using a compound for closely conforming to the surrounding surface. Such operation is referred to as "surface-conditioning" or "skin-conditioning".
The surface-conditioning is generally effected in such manner that if the orange peel is finer and larger in number than that of the surrounding surface then a raised portion is firstly sanded by using a water-proof abrasive paper of No. 1000 (P1000) to No. 2000 for conforming to the surrounding surface. Then, any sanding trace produced by this water-proof abrasive paper is eliminated by using a fine compound buffing process. In addition, any polishing trace produced by this fine compound buffing is eliminated, and at the same time, the surface-conditioning is effected with the use of a very fine compound buffing process. Finally, polishing is conducted by using a super fine compound.
In general, in the automobile repairing industry, only a few repair shops or painters have a complete painting booth equipped with an air cleaner, but most of the repair shops or painters have a simplified painting booth or no such booth. Therefore, it may frequently happen that fine particles or dust in the air are deposited on the painted surface and tend to absorb the paint on the surrounding surface to form a raised portion on the surface or make the surface rough. When such a surface is sanded by using the prior art water-proof abrasive paper, some sanding trace may remain thereon. In addition, the roughness on the recess portion can not be eliminated by use of such water-proof abrasive paper. Such roughness on the recess portion and the sanding trace can be eliminated only by using the compound, thereby effecting surface-conditioning.
The buffing process is generally performed using a polisher which is electrically or pneumatically driven at the rotation speed of 1500 to 3000 rpm. A towel buff, a wool buff or a sponge buff is commonly used between the polisher and the painted surface. A compound used in the buffing process consists of an emulsion including particles that have lower hardness and are likely to be worn and collapsed for the purpose of providing the gloss. The buffing process is performed while dropping such liquid compound onto the painted surface.
The water-proof abrasive paper of the finest grains currently available is No. 2000. Any sanding trace produced by such abrasive paper is generally eliminated by the buffing process using the compound.
Because of free particles used for such buffing process, the polishing efficiency is lower, and a longer period of time and much labor is are necessary. On the other hand, the sanding process using the abrasive paper or cloth provides higher efficiency, but the sanding trace produced thereby becomes coarser. Furthermore, such abrasive paper or cloth can sand only a raised portion of the orange peel, but not a recess portion thereof.
In the prior art, another abrasive member has been proposed in which a flexible adhesive layer having abrasive particles incorporated therein is deposited onto a film or any other layers. Such an abrasive member has a deficiency in that the abrasive particles may be removed earlier, leading to loss of the abrasion capability, and that the sanding of a recess portion can not be attained. A further abrasive member has also been proposed in which abrasive particles are deposited onto a sponge pad in the same manner as the case where they are deposited onto a paper or cloth. Such abrasive member, however, is not practical because of coarse sanding trace and a lot of waste produced after it is used.
In the prior art, the buffing process including the surface-conditioning using the compound takes the longer time of, for example, at least 20 minutes, and even 90 minutes if an orange peel is present.
In view of the above, the object of the present invention is to provide an abrasive sheet, and method of manufacturing the same, which can solve the prior art problems as described above. More particularly, the object of the present invention is to provide a new and improved abrasive sheet it which it provides higher abrasive capability or sanding power and produces a finer sanding trace which can easily be polished and smoothed out with a compound. The abrasive sheet can completely sand any recess portion of the orange peel.